Fatigue crack growth of aluminium alloy 7075-T651 under proportional and non-proportional mixed mode I and II loads

This study aims to experimentally investigate fatigue growth behaviour in AA7075-T651 under proportional and non-proportional mixed mode I and II loads. Fatigue tests were performed under cyclic tension and torsion using a thin-walled tubular specimen with a key-hole style crack starter. After the generation of a single-side mode I pre-crack, varied forms of mixed mode loads were applied, which in most cases led to coplanar growth for a short...